Determining the trajectory of a block that falls down on a slope is not straightforward due to the high number of variables involved. Because of this, the appropriate understanding of how these variables may affect the trajectories is required. In this work, we estimate some magnitudes that affect the trajectories of the blocks such as the coefficient of restitution and the energy thresholds for fragmentation of the blocks among others. We have chosen the controlled scenario of a quarry in which targets and high speed video cameras were arranged to capture images of the blocks falling from the top of a slope. The position of the blocks over time has been measured from video frames applying photogrammetric methods. From here, the velocities and the accelerations have been determined, and with the estimated mass of each block, we have calculated the energy balance.http://dx.doi.org/10.4995/CIGeo2017.2017.6617